Scaffold machine



pr 2S? 31936 P. HolTsMA f scAFFoLD MACHINE Filed Nov. 26, 1935 INVENTOR, Pete# /'aziis' ma,

BY g

` ATTORNEY.

Cil

Patented Apr. 28, 1936 UNITED STATES PATENT OFFE SCAFFOLD MACHINE' Peter Hoitsma, Paterson, N. J.

Application November 26, 1935, Serial No. 51,586

3 Claims.

In my Patent No. 1,441,806 there is set forth a scaffold machine comprising, with a load-carrying member to flank an upright and having means to engage the latter normally free to move upwardly but not downwardly on the upright, lifting means including a lever pivotally connected with said member and movable up and down and means in which the lever is fulcrumed having a gripper engaging the upright and normally free to move upwardly but not downwardly thereon, said lever having means to bear laterally on the upright. To raise the load-carrying member, the lever is depressed, being then supported by the third-named means and so lifting said member, at the end of which movement the first-named means obtains a fresh grip on the upright. To descend, the lever is held elevated to obtain thereby a slip grip on the upright while its gripper is held retracted (as by hand) and the first-named means is caused (as by the operators foot) to disengage the upright. In practice, it has been found that there is no danger of such a mechanism getting out of control and unduly falling during the attempt to descend provided that when said first-named means is depressed the operator, holding the gripper retracted, also holds the lever in grip-ping relation to the upright, releasing the rst-named means or the gripper when the desired descent has been accomplished. Nevertheless, it is desirable, especially when the mechanism is used by timid operators, to eliminate any hazard in this respect, and this indicates the principal object of the present invention.

In the drawing,

Fig. 1 is a side elevation of an upright and apparatus thereon constructed in accordance with the present invention;

Fig. 2 is an elevation as viewed from the right in Fig. 1;

Fig. 3 is a fragmentary isometric view of the lower end of the apparatus; Fig, 4 is a section on a horizontal line immediately above the element I'I in Fig. 1; and

Fig. is a fragmentary section on line 5, Fig. 4.

Let I be an upright, as a 4x4 of wood, to rest on the ground. The load-carrying member comprises the following parts: an angle-iron element 2 having an inverted U-shaped form; an arm 3 also having a U-shaped form and bolted to member 2, as at 4; angle-iron braces 5 (only one being shown) bolted at 6-6 to member 2 and arm 3; a pair of plates l' secured by bolt 4 and a bolt 8 to the upper end of member 2, the plates straddling the upright and one of them having a rigid upstanding extension 9 in the form of a plate shaped stirrup 23.

being square in cross-section and presenting an Y edge to the upright; the shackle is normally urged to the position shown in Fig. 1, so that both bars press against the upright, by a spring I3 coiled about the bolt II and arranged to engage members 2 and I0, as shown in Fig. 3. The arm 3 is incidentally shown capable of folding on the bolt 6 which joins the arm and brace 5, when extended its pivoted or folding part being adapted to bear against a bolt I4.

So much is not materially different from my Y said patented construction. As for the lifting means:

A shackle or gripper, arranged above the loadcarrying member and embracing the upright, is constructed as follows: IE is a U-shaped member which straddles the upright. At one side of the upright it is spanned by a square bar I6 xed against rotation therein and presenting an edge to the upright. At the other side of the upright there spans and is journaled in said member a bar Il. The portion Ila of the bar between and of shorter length than the spacing of the extremities of member I5 is square in cross-section and twisted so as to form a steeply pitched helix whereas its end portions I 'Ib are reduced and form trunnions which are journaled in said eX- tremities and one of which may be prolonged and bent to form a crank I'Ic; one of said trunnions is for a part of its length, as at I'I, square in cross-section to t a corresponding square hole I5a (Fig. 5) in the member I5, thus forming in effect a spline. Pivoted on a bolt I8 outward of the bar I6 is a U-shaped link member I9 whose extremities carry a bolt 20 which affords a fulcrum for the lever 2| and may bear against the upright, the shorter arm ofthe lever being pivotally connected with the load-carrying member by a pin 22 which is removably received in the curl 9a of the extension 9 of its plate 1, and the longer arm of the lever preferably having a U- A spring 24 is coiled about the bolt i8 and bears against member I5 and link member I9, tending to maintain them alined with each other or so that member I5 assumes the position shown in'Figs. 1 and 2.

It will be understood that the upright and the described mechanism thereon are duplicated and that the planking to support the workmen is arranged on the arms 3. The upper shackle and the lever in the present instance project at right angles with respect to arm 3 and when the entire equipment comprising the duplicated uprights and mechanism, with the planking, is assembled the levers are preferably arranged so that each projects toward the other upright so as to be in convenient reach of the workmen.

Operation- The load is of course normally supported by the lower shackle, held in the position of Figs. 1 and 2 with its bars I2 bighting into the wood of the upright. To cause the mechanism to rise the lever is depressed by the operators foot applied to its stirrup 23, the load-carrying member, with the lower shackle, sliding up on the upright until the lever reaches its downward limit, whereupon said member remains supported by the shackle. To cause it to rise another stage, the lever is depressed and the above operation repeated.

To descend the operator sits on the platform or planking and with his foot releases the lower shackle, leaving the load supported by the upper shackle or gripper. He then turns the bar I'I by means of its handle I'Ic in the direction to cause said bar (which is in efect a roller) to roll down the upright, such action tending to release the grip of the gripper on the upright incident to the action of spring 24 and the load. In this Way the upper shackle or gripper, carrying the load, creeps down the upright.

As indicated, the bar I'I is in effect a roller and whatever shape its portion I'Ia may have I nd in practice that, when the upper shackle or gripper is under load, the elements I6 and I1 obtain a grip on the upright of such character that it requires eiort, additional to that incident to the load, to turn the element I1, as by its handle I'Ic. However, if the bar is shaped as described, or so as to present iiutes, as I'Iy, helically developed around its axis and steeply pitched, all danger of its turning merely under the weight of the load is completely prevented and still it requires very little effort on the part of the operator to turn it by means of its handle.

If the operator desires additional assurance of safety when the mechanism is stationary or during rise, element I'I can be shifted lengthwise until it becomes splined with member I5 by its square portion IIm engaging in the square hole 15a, so that it is thus positively locked to member I5 against rotation.

Having thus fully described my invention what I claim is:

1. In combination, with an upright and with a load-carrying member having releasable means to grip the upright, a lever pivotally connected with said member and means in which the lever is fulcrumed including a member embracing, and having means to engage one vertical face of, the upright and a roller journaled in the latter member in transverse relation to and bearing against the opposite face of the upright and having a handle by which to rotate such roller, the portion of the roller which bears against the upright being polygonal in cross-section.

2. In combination, with an upright and with a load-carrying member having releasable means to grip the upright, a lever pivotally connected with said member and means in Which the lever is fulcrumed including a member embracing, and having means to engage one vertical face of, the upright and a roller journaled in the latter memer in transverse relation to and bearing against the opposite face of the upright and having a I handle by which to rotate such roller, the portion of the roller which bears against the upright being polygonal in cross-section and twisted to present flutes helically developed around the axis of the roller and steeply pitched.

3. In combination, with an upright and with a load-carrying member having releasable means to grip the upright, a lever pivotally connected with said member and means in which the lever is fulcrumed including a member embracing, and

having means to engage one vertical face of, the upright and a roller journaled in the latter member in transverse relation to and bearing against the opposite face of the upright and having a handle by which to rotate such roller, said roller being movable axially in the latter member and the roller and such member having means to form a spline connection between them when the roller is so moved.

PETER HOITSMA. 

